body{font-family:Arial,Helvetica,sans-serif;background:#f6f8fa;color:#222}
.container{max-width:900px;margin:24px auto;padding:18px;background:#fff;border-radius:6px;box-shadow:0 1px 4px rgba(0,0,0,0.08)}
h1{margin-top:0}
label{display:block;margin:6px 0}
input,select,button{padding:6px;margin-left:8px}
button{cursor:pointer}
#billsTable{width:100%;border-collapse:collapse}
#billsTable th,#billsTable td{border:1px solid #ddd;padding:8px;text-align:left}

/* Bootstrap compatibility tweaks */
.card{border-radius:.5rem}
.card .card-body{padding:1rem}
.table td, .table th{vertical-align:middle}
.form-control, .form-select{margin-left:0}
